Electronic devices with FDP (Flat Panel Displays) based on different technologies, such as PDP (Plasma Display Panel) and LCD (Liquid Crystal Display) have existed for a number of years on the market now. While offering superior sharpness and level of detail compared to previously existing cathode ray tubes there is a constant need to reduce their power consumption in portable electronic devices. Mainly the power consumption of FDP displays stems from their backlight function used in order to illumine the display when it is used in unfavourable lighting conditions.
In recent years, electronic devices with displays using so called OLED (Organic Light Emitting Display) have appeared on the market eliminating the need of a backlight function and, under special circumstances, possibly also the power consumption of such a display. However, the cost of OLED displays is still higher than that of LCD displays with backlight and at the same time OLED displays may show signs of colour shifting with time. Thus, LCD-based FDP displays will probably still remain the dominant display technology on the market for some time.
Now regarding LCD displays In low lighting conditions which typically occur indoors, a display with high brightness and contrast is desirable, i.e. a fully transmissive display. On the other hand, it is also desirable to have a display that is clearly visible in bright light as well.
Since so far these requirements have been in conflict, design engineers have developed displays which provide a compromise between fully transmissive and fully reflective displays offering satisfactory brightness and contrast in most lighting conditions.
Therefore, the selection of display for an electronic device has been influenced by the lighting conditions in which the display was to be used.
Handheld electronic devices are normally used in all possible lighting conditions. Hence there is a need to develop a display for portable electronic devices which provide good brightness and contrast in all lighting conditions.